while (my @row = $sth->fetchrow_array()){
							my $parser = XML::LibXML->new();
							my $doc = $parser->parse($row[0]);
							my $root = $doc->documentElement();

							my %linked_counts_by_abbr;
							for my $usage_node ($root->findnodes('/BookReferences/BookUsage')) {
    							my $abbr         = $usage_node->getAttribute('BookAbbr');
    							my $linked_count = $usage_node->getAttribute('LinkedCount');
    							$linked_counts_by_abbr{$abbr} += $linked_count;
							}
							foreach (my ($key, $value) = each %linked_counts_by_abbr){
								print OUTPUT "$key => $value\n";
							}
						}